![](https://coimages.sciencemuseumgroup.org.uk/320/613/large_thumbnail_smg00032012.jpg)
![](https://coimages.sciencemuseumgroup.org.uk/320/613/large_thumbnail_smg00032012.jpg)
![](https://coimages.sciencemuseumgroup.org.uk/374/634/large_thumbnail_smg00084548.jpg)
Concave Rowland diffraction grating on speculum metal
1894
![](https://coimages.sciencemuseumgroup.org.uk/374/645/large_thumbnail_smg00084559.jpg)
Concave Rowland diffraction grating on speculum metal
1898
![](https://coimages.sciencemuseumgroup.org.uk/374/641/large_thumbnail_smg00084555.jpg)
Plane Rowland diffraction grating on speculum metal
1895-1909 (estimated)
![](https://coimages.sciencemuseumgroup.org.uk/374/644/large_thumbnail_smg00084558.jpg)
Concave Rowland-type diffraction grating on speculum metal
1882-1899
![](https://coimages.sciencemuseumgroup.org.uk/374/593/large_thumbnail_smg00084095.jpg)
Concave Rowland diffraction grating on speculum metal
1899
![](https://coimages.sciencemuseumgroup.org.uk/374/640/large_thumbnail_smg00084554.jpg)
Concave Rowland diffraction grating on speculum metal
1894
![](https://coimages.sciencemuseumgroup.org.uk/374/639/large_thumbnail_smg00084553.jpg)
Concave Rowland-type diffraction grating on speculum metal
1882-1909 (estimated)
![](https://coimages.sciencemuseumgroup.org.uk/374/643/large_thumbnail_smg00084557.jpg)
Concave Rowland-type diffraction grating on speculum metal
1926, April
![](https://coimages.sciencemuseumgroup.org.uk/374/637/large_thumbnail_smg00084551.jpg)
Concave Rowland diffraction grating on speculum metal
1882, Nov 6
Plane diffraction grating with 14
1890